Fern | Description, Features, Evolution, & Taxonomy | Britannica
Fern, class of several thousand species of nonflowering vascular plants that reproduce by spores. Ferns have true roots, stems, and complex leaves and constitute an ancient division of plants. Learn about their physical characteristics, life cycle, …
List of ferns | Types, Species, Varieties | Britannica
Ferns (division Pteridophyta) are an ancient group of nonflowering vascular plants. They have true roots, stems, and complex leaves and reproduce by spores. Ferns can be found nearly worldwide and more than 9,000 extant species are known to science.
Fern - Spore Dispersal, Photosynthesis, Moisture | Britannica
Fern - Spore Dispersal, Photosynthesis, Moisture: Ecologically, ferns are most commonly plants of shaded damp forests in both temperate and tropical zones. They may show structural adaptations to rocky habitats or to living as epiphytes.
Fern - Shape, Structure, Reproduction | Britannica
Fern - Shape, Structure, Reproduction: The basic spore shape is tetrahedral. Most ferns are homosporous, while a few have dimorphic spores. Gametophytes form when the spore wall cracks under appropriate moist conditions.
Plant - Ferns, Spores, Vascular | Britannica
2024年11月18日 · Plant - Ferns, Spores, Vascular: Ferns (class Polypodiopsida) are a diverse group of plants with a worldwide distribution, common in tropical and subtropical regions. Subclass Polypodiidae (leptosporangiate ferns) include the orders Psilotales (whisk ferns), Equisetales (horsetails and scouring rushes), and Marattiales (giant ferns).
fern - Students | Britannica Kids | Homework Help
The familiar fern plant is the sporophyte. To summarize: ferns produce spores; spores produce prothallia; in the prothallia grow eggs and sperm; sperm fertilize eggs; fertilized eggs grow into large fern plants. Ferns are generally classed in their own division, Pteridophyta.
Fern - Spore, Rhizome, Frond | Britannica
Fern - Spore, Rhizome, Frond: Steles exhibit diverse patterns: most common ferns possess a dictyostele, separated by regions known as leaf gaps; there are also numerous siphonostelic ferns and some protostelic ferns.
Fern - Medicinal, Ornamental, Food | Britannica
Fern - Medicinal, Ornamental, Food: Many species are a source of food and medicine. The greatest economic value is in horticulture and biological research. The typical fern, a sporophyte, consists of stem, leaf, and root, usually perennial, and reproduces vegetatively.
Fern - Evolution, Development, Reproduction | Britannica
Fern - Evolution, Development, Reproduction: The actual origins of the vegetative organs of ferns are still unknown. It is suggested that the original fern stem was protostelic; the leaf is equally or even more problematic as to its ultimate origin.
fern - Kids | Britannica Kids | Homework Help
Ferns are flowerless green plants. They are usually easy to recognize by the featherlike shape of their leaves, which are called fronds. Ferns reproduce by spores rather than by seeds. Some plants that are called ferns, such as asparagus ferns, reproduce by seeds and are not true ferns.